Organisms in Domains Bacteria and Archaea – Similarities and Differences

The similarities and differences between organisms in the domains bacteria and archaea

Archaea and bacteria are both single-celled microorganisms known as prokaryotes but this is one of the unique features they do have in common (Hall-Stoodley, 2004). Despite the fact that they both look imprecisely alike when viewed using a microscope, each one of them represents an absolutely different group of organisms. In fact, archaea are different from bacteria just as much as human beings do, i.e. in terms of their genetic structure and biochemistry. Archaea and bacteria have different cell membranes and cell structures; Comparable to bacteria archaea lack interior membranes but both use flagella to swim and have cell wall, another difference is that archaea are found in life-threatening environments where most bacteria could not survive i.e. archaea can survive in extreme and harsh environments like salty lakes, hot springs, oceans and marshlands, whereas bacteria are  found in soil, radioactive waste waters, organic matter, Earth’s crust, bodies of animals and plants.

Bacteria cell walls have a substance known as peptidoglycan, while the cell walls of archaea uses ether linked lipids. Archaea and bacteria also differ from each other because the cell membranes of archaea have an exceptional structure and do not contain the same fats or lipids that are found in the cell membranes of the other organism. Archaea membranes contains a substance called isoprene. This substance creates heat-resistant structures in the membrane of the archaea unlike the bacterial cell membranes which lack the substance.

From the Inside of the archaea, there are protein-synthesizing molecules called ribosomes which are different from those found in the bacteria.

From their reproductive point of view, archaea and bacteria both reproduces asexually through a process of binary fission, fragmentation, and budding but bacteria have a unique ability to create spores so as to remain in a dormant mode over years, a characteristic that is not showed by archaea.


Hall-Stoodley L, Costerton JW, Stoodley P; Costerton; Stoodley (2004). “Bacterial biofilms: from the natural environment to infectious diseases”. Nature Reviews Microbiology 2 (2): 95–108.

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